A man under police investigation for allegedly sexually abusing boys at a Sydney Jewish school has said senior rabbis knew of his actions but failed to report them to authorities.

NSW police are investigating allegations two men associated with the school community surrounding the ultra-orthodox Yeshiva Centre in Bondi sexually abused children during the 1970s and '80s.

Fairfax Media understands there are at least four alleged victims of one man. The alleged sexual abuse occurred at the boys' homes and at a camp organised by the Yeshiva Centre.

When news of the NSW police investigation was first reported last week, the Bondi Yeshiva Centre's spiritual leader, Rabbi Pinchus Feldman, said he was shocked to learn of the allegations. ''I do not recall anyone ever coming to me with such a problem. I am shocked to hear that anything of this nature has taken place here,'' he said.

However, one of the alleged perpetrators is known to have recently told one of his victims that he was questioned by Rabbi Feldman about 25 years ago over his alleged sexual abuse of boys. ''He [Rabbi Feldman] just told me it shouldn't happen and I should take steps to avoid it,'' the accused man told his alleged victim. ''It was a once-off conversation in his office.''

Rabbi Feldman did not respond to phone calls or emails from Fairfax Media on Tuesday.

It is understood one or more other senior figures in Sydney's Yeshiva Centre were also aware of the alleged abuse in the 1980s but failed to contact police. The alleged offender also told his victim that he had abused several boys, something he said he was now deeply sorry about.

NSW police this month confirmed it had been investigating child sexual abuse allegations involving the Bondi Jewish community since early last year.

The investigation began after NSW detectives received information from Victorian police who had been probing abuse allegations at Melbourne's Yeshiva College since 2011.

It is understood that at least one alleged victim of the Sydney sexual assaults has provided a statement to NSW police.

The attitudes of senior Jewish leaders regarding the reporting of child sexual abuse have been under scrutiny in recent months after comments by senior Chabad rabbi Manis Friedman playing down the effects of abuse.

Based in the US, Rabbi Friedman compared abuse to having a case of diarrhoea. He later apologised, saying his intention was to help empower victims to move forward.